WO2014024892A1

WO2014024892A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: WO2014024892A1
Application number: PCT/JP2013/071282
Authority: WO
Inventors: 隆之根木; 宏之桜井; 皇晶筒井
Original assignee: 日産化学工業株式会社
Priority date: 2012-08-10
Filing date: 2013-08-06
Publication date: 2014-02-13
Also published as: TWI485201B; CN104704421B; KR20150043359A; JP6319581B2; TW201425471A; KR102096126B1; JPWO2014024892A1; CN104704421A

Abstract

Provided is a liquid crystal alignment agent that comprises a solvent and at least one kind of polymer selected from among: a polyamic acid obtained by causing a polymerization reaction between a tetracarboxylic dianhydride that is represented by formula (1) and a diamine component; and a polyimide obtained by imidizing this polyamic acid.

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

The present invention relates to a liquid crystal aligning agent used when producing a liquid crystal aligning film, a liquid crystal aligning film using the same, and a liquid crystal display element.

Liquid crystal display elements used for liquid crystal televisions and liquid crystal displays are now widely used as thin and light display devices. As a liquid crystal alignment film for aligning liquid crystal, a so-called polyamic acid (also referred to as polyamic acid), a polyimide precursor such as polyamic acid ester, or a liquid crystal aligning agent mainly composed of a polyimide solution is applied to a glass substrate or the like and baked. A polyimide-based liquid crystal alignment film is mainly used.

In order to improve the display characteristics of such liquid crystal display elements, methods such as changing the structure of polyamic acid, polyamic acid ester and polyimide, polyamic acid with different characteristics, blend of polyamic acid ester and polyimide, adding additives, etc. As a result, liquid crystal orientation, electrical characteristics, etc. are improved, and the pretilt angle is controlled (see Patent Document 1, etc.).

JP 2011-100099 A

However, as liquid crystal display elements have higher performance, larger areas, and power-saving display devices, the characteristics required for liquid crystal alignment films have become stricter, and the resistance of liquid crystal display elements to exposure to ultraviolet rays has also increased. Desired. Specifically, for example, when performing the drop injection method in liquid crystal injection / encapsulation, when the sealing material for sealing is irradiated with ultraviolet rays, the liquid crystal alignment film in the image forming region may be irradiated with ultraviolet rays. is there. When aligning the liquid crystal alignment film by light irradiation, the liquid crystal alignment film is irradiated with ultraviolet rays (UV) in the alignment treatment step. Some liquid crystal display elements such as the vertical alignment (VA) system include a step of irradiating ultraviolet rays while applying a voltage to liquid crystal molecules in the manufacturing process. In addition, the liquid crystal display element may be exposed to ultraviolet rays from the outside during use. When the liquid crystal alignment film is not resistant to exposure to these ultraviolet rays, there arises a problem that electrical characteristics such as voltage holding ratio deteriorate.

An object of the present invention is to provide a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element capable of obtaining a liquid crystal alignment film having excellent ultraviolet resistance. .

As a result of diligent research, the present inventors have found that a liquid crystal aligning agent containing a polyamic acid or polyimide using a tetracarboxylic dianhydride having a specific structure as a raw material and a solvent is very As a result, the present invention has been found to be effective.

That is, the present invention has the following gist.

1. At least one polymer selected from a polyamic acid obtained by polymerizing a tetracarboxylic dianhydride represented by the following formula (1) and a diamine component and a polyimide obtained by imidizing the polyamic acid; And a liquid crystal aligning agent containing a solvent.

2. 2. The liquid crystal aligning agent according to 1, wherein the polymer is polyimide.

3. A liquid crystal alignment film obtained by using the liquid crystal aligning agent described in 3.1 or 2.

4. A liquid crystal display element comprising the liquid crystal alignment film according to 4.3.

The liquid crystal alignment film obtained by using the liquid crystal aligning agent of the present invention has excellent resistance to ultraviolet rays. Therefore, for example, even when used as a liquid crystal alignment film of a liquid crystal display element including a step of irradiating ultraviolet rays in the manufacturing process, the deterioration of electric characteristics such as voltage holding ratio is suppressed in the manufacturing process, and the liquid crystal display having good electric characteristics An element can be provided. Further, even when used as a liquid crystal alignment film of a liquid crystal display element used in an environment exposed to ultraviolet rays, deterioration of electric characteristics such as voltage holding ratio is suppressed, and a liquid crystal display element having good electric characteristics is obtained.

The present invention is described in detail below.
The liquid crystal aligning agent of the present invention includes a polyamic acid obtained by polymerizing a tetracarboxylic dianhydride represented by the above formula (1) and a diamine component, and a polyimide obtained by imidizing this polyamic acid. It contains at least one polymer selected from the above and a solvent. The liquid crystal alignment agent is a solution for producing a liquid crystal alignment film, and the liquid crystal alignment film is a film for aligning liquid crystals in a predetermined direction.

In the formula (1), it is preferable that —NH— bonded to the benzene ring is present at the para position or the meta position.

A polyamic acid is obtained by polymerizing the tetracarboxylic dianhydride represented by the formula (1) with a diamine component. Moreover, a polyimide is obtained by imidating the obtained polyamic acid.

The liquid crystal aligning agent of the present invention is a polyamic acid obtained by polymerizing the tetracarboxylic dianhydride represented by the formula (1) and a diamine component, or a polyimide obtained by imidizing this polyamic acid. And a solvent. Thus, by using the polyamic acid and polyimide which use the tetracarboxylic dianhydride represented by Formula (1) as a raw material, and the liquid crystal aligning agent containing a solvent, as shown in the Example mentioned later, ultraviolet ( It is possible to obtain a liquid crystal alignment film that is excellent in UV resistance and in which deterioration of electrical characteristics such as voltage holding ratio (VHR) due to UV exposure is suppressed. Accordingly, it is possible to provide a liquid crystal display element having excellent electrical characteristics in which deterioration of electrical characteristics such as voltage holding ratio is suppressed even when UV is irradiated in the manufacturing process or used in an environment exposed to UV. Can do.

Moreover, the polyimide which uses the tetracarboxylic dianhydride represented by Formula (1) as a raw material, and the liquid crystal aligning agent containing a solvent have high coating-film uniformity at the time of apply | coating a liquid crystal aligning agent. Generation of polymer aggregates (also called whitening / aggregation) hardly occurs at the end of the film surface. Of course, the whitening and aggregation of the liquid crystal aligning agent containing a polyamic acid using a tetracarboxylic dianhydride represented by the formula (1) and a solvent hardly occur. In addition, a polyimide using tetracarboxylic dianhydride represented by the formula (1) as a raw material has solubility in a solvent used for a liquid crystal aligning agent such as N-methyl-2-pyrrolidone or 2-butoxyethanol. Even if the liquid crystal aligning agent is allowed to stand for a long time, it does not precipitate and has high storage stability.

The production method of the tetracarboxylic dianhydride represented by the formula (1) is not particularly limited. For example, 1,2,4-cyclohexanetricarboxylic acid-1,2-anhydride 4-chloride and phenylenediamine It can manufacture by making these react. Specifically, the production method described in JP2012-72121A can be mentioned.

Further, together with the tetracarboxylic dianhydride represented by the formula (1), a tetracarboxylic dianhydride other than the tetracarboxylic dianhydride represented by the formula (1) (hereinafter, other tetracarboxylic dianhydrides). May also be reacted with a diamine component. At that time, the tetracarboxylic dianhydride represented by the formula (1) is preferably used in an amount of 60 to 95 mol% of the total amount of the tetracarboxylic dianhydride components used for the synthesis of the polyamic acid, more preferably. Is a tetracarboxylic dianhydride in which 70 to 90 mol% of the tetracarboxylic dianhydride component is represented by the formula (1). In addition, the tetracarboxylic dianhydride represented by Formula (1) and other tetracarboxylic dianhydrides are collectively described as a tetracarboxylic dianhydride component.

Examples of other tetracarboxylic dianhydrides include tetracarboxylic dianhydrides represented by the following formula (2).

(In the formula (2), Z ₁ is a tetravalent organic group having 4 to 13 carbon atoms containing a non-aromatic cyclic hydrocarbon group having 4 to 6 carbon atoms.)

In formula (2), specific examples of Z ₁ include tetravalent organic groups represented by the following formulas (2a) to (2j).

(In the formula (2a), Z ₂ to Z ₅ are a hydrogen atom, a methyl group, a chlorine atom or a benzene ring, which may be the same or different. In the formula (2g), Z ₆ and Z ₇ Are hydrogen atoms or methyl groups, which may be the same or different.

In formula (2), particularly preferred structure of Z ₁ is represented by formula (2a), formula (2c), formula (2d), formula (2e), formula (2f) or formula from the viewpoint of polymerization reactivity and ease of synthesis. (2g). Among these, the formula (2a), the formula (2e), the formula (2f), or the formula (2g) is preferable.

Further, the ratio of the tetracarboxylic dianhydride represented by the formula (2) to the total amount of the tetracarboxylic dianhydride component is not particularly limited. For example, 5 to 40 mol% of the total amount of the tetracarboxylic dianhydride component is It is preferably a tetracarboxylic dianhydride represented by the formula (2), more preferably 10 to 30 mol%.

Other tetracarboxylic dianhydrides other than the tetracarboxylic dianhydride represented by the above formula (2) include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6 -Naphthalene tetracarboxylic acid, 1,4,5,8-naphthalene tetracarboxylic acid, 2,3,6,7-anthracene tetracarboxylic acid, 1,2,5,6-anthracene tetracarboxylic acid, 3,3 ', 4,4′-biphenyltetracarboxylic acid, 2,3,3 ′, 4′-biphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 3,3 ′, 4,4′-benzophenonetetracarboxylic Acid, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4-dicarboxyphenyl) pro 1,1,1,3,3,3-hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethylsilane, bis (3 4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis (3,4-dicarboxyphenyl) pyridine, 3,3 ′, 4,4′-diphenylsulfone And dianhydrides of tetracarboxylic acid, 3,4,9,10-perylenetetracarboxylic acid or 1,3-diphenyl-1,2,3,4-cyclobutanetetracarboxylic acid.

In addition, the polyamic acid, the tetracarboxylic dianhydride represented by the above formula (1) used as a raw material for polyimide, and other tetracarboxylic dianhydrides may each be one kind or two or more kinds. But you can.

The diamine component to be reacted with a tetracarboxylic dianhydride component such as tetracarboxylic dianhydride represented by the formula (1) is not particularly limited, and a diamine generally used for a liquid crystal aligning agent can be used. . Examples of general diamines include general-purpose diamines, diamines having side chains for vertically aligning liquid crystals, diamines that allow liquid crystals to exhibit a high pretilt angle, and diamines having photoreactive groups.

Examples of general-purpose diamines include p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, and 2,4-dimethyl- m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,5-diaminophenol, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2, 4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl 3,3′-dihydroxy-4,4′-diaminobiphenyl, 3,3′-dicarboxy 4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-biphenyl, 3,3'-trifluoromethyl-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3 '-Diaminobiphenyl, 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'- Diaminodiphenylmethane, 2,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether 4,4′-sulfonyldianiline, 3,3 ′ Sulfonyl dianiline, bis (4-aminophenyl) silane, bis (3-aminophenyl) silane, dimethyl-bis (4-aminophenyl) silane, dimethyl-bis (3-aminophenyl) silane, 4,4'-thiodianiline 3,3′-thiodianiline, 4,4′-diaminodiphenylamine, 3,3′-diaminodiphenylamine, 3,4′-diaminodiphenylamine, 2,2′-diaminodiphenylamine, 2,3′-diaminodiphenylamine, N— Methyl (4,4'-diaminodiphenyl) amine, N-methyl (3,3'-diaminodiphenyl) amine, N-methyl (3,4'-diaminodiphenyl) amine, N-methyl (2,2'-diamino) Diphenyl) amine, N-methyl (2,3′-diaminodiphenyl) amine, 4,4 '-Diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 1,4-diaminonaphthalene, 2,2'-diaminobenzophenone, 2,3'-diaminobenzophenone, 1,5-diaminonaphthalene 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 2,8-diaminonaphthalene, 1,2-bis (4-aminophenyl) ethane, 1,2-bis (3-aminophenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenyl) Propane, 1,4-bis (4-aminophenyl) butane, 1,4-bis (3-aminophenyl) butane , Bis (3,5-diethyl-4-aminophenyl) methane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4 -Aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (4-aminobenzyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4'- [1,4-phenylenebis (methylene)] dianiline, 4,4 ′-[1,3-phenylenebis (methylene)] dianiline, 3,4 ′-[1,4-phenylenebis (methylene)] dianiline, 3 , 4 '-[1,3-phenylenebis (methylene)] dianiline, 3,3'-[1,4-phenylenebis (methylene)] dianiline, 3,3 '-[1,3-phenylenebis (me Len)] dianiline, 1,4-phenylenebis [(4-aminophenyl) methanone], 1,4-phenylenebis [(3-aminophenyl) methanone], 1,3-phenylenebis [(4-aminophenyl) Methanone], 1,3-phenylenebis [(3-aminophenyl) methanone], 1,4-phenylenebis (4-aminobenzoate), 1,4-phenylenebis (3-aminobenzoate), 1,3-phenylene Bis (4-aminobenzoate), 1,3-phenylenebis (3-aminobenzoate), bis (4-aminophenyl) terephthalate, bis (3-aminophenyl) terephthalate, bis (4-aminophenyl) isophthalate, bis (3-aminophenyl) isophthalate, N, N ′-(1,4-phenylene) bis (4-amino Nobenzamide), N, N ′-(1,3-phenylene) bis (4-aminobenzamide), N, N ′-(1,4-phenylene) bis (3-aminobenzamide), N, N ′-( 1,3-phenylene) bis (3-aminobenzamide), N, N′-bis (4-aminophenyl) terephthalamide, N, N′-bis (3-aminophenyl) terephthalamide, N, N′-bis (4-aminophenyl) isophthalamide, N, N′-bis (3-aminophenyl) isophthalamide, 9,10-bis (4-aminophenyl) anthracene, 4,4′-bis (4-aminophenoxy) diphenyl Sulfone, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-bis [4- (4-aminophenoxy) phenyl] hexafluoro Lopan, 2,2'-bis (4-aminophenyl) hexafluoropropane, 2,2'-bis (3-aminophenyl) hexafluoropropane, 2,2'-bis (3-amino-4-methylphenyl) Hexafluoropropane, 2,2′-bis (4-aminophenyl) propane, 2,2′-bis (3-aminophenyl) propane, 2,2′-bis (3-amino-4-methylphenyl) propane, 3,5-diaminobenzoic acid, 2,5-diaminobenzoic acid, 1,3-bis (4-aminophenoxy) propane, 1,3-bis (3-aminophenoxy) propane, 1,4-bis (4- Aminophenoxy) butane, 1,4-bis (3-aminophenoxy) butane, 1,5-bis (4-aminophenoxy) pentane, 1,5-bis (3-aminophenoxy) Lanthanum, 1,6-bis (4-aminophenoxy) hexane, 1,6-bis (3-aminophenoxy) hexane, 1,7-bis (4-aminophenoxy) heptane, 1,7- (3- Aminophenoxy) heptane, 1,8-bis (4-aminophenoxy) octane, 1,8-bis (3-aminophenoxy) octane, 1,9-bis (4-aminophenoxy) nonane, 1,9-bis ( 3-aminophenoxy) nonane, 1,10- (4-aminophenoxy) decane, 1,10- (3-aminophenoxy) decane, 1,11- (4-aminophenoxy) undecane, 1,11- (3- Aromatic diamines such as aminophenoxy) undecane, 1,12- (4-aminophenoxy) dodecane, 1,12- (3-aminophenoxy) dodecane, bis (4-amino Nocyclohexyl) methane, alicyclic diamines such as bis (4-amino-3-methylcyclohexyl) methane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diamino Aliphatic diamines such as hexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane It is done.

Such a general-purpose diamine is preferably used in an amount of 50 to 95 mol% of the diamine component used for the synthesis of the polyamic acid, and more preferably 70 to 90 mol% of the diamine component.

As a diamine having a side chain that vertically aligns the liquid crystal or a diamine that develops a high pretilt angle in the liquid crystal, a long chain alkyl group, a group having a ring structure or a branched structure in the middle of the long chain alkyl group, a steroid group, Examples thereof include diamines having, as a side chain, a group in which some or all of the hydrogen atoms in these groups are replaced with fluorine atoms. Specific examples include diamines represented by the following formulas (3), (4), (5), and (6), but are not limited thereto.

(In the formula (3), l, m and n each independently represents an integer of 0 or 1, and R ³ represents an alkylene group having 2 to 6 carbon atoms, —O—, —COO—, —OCO—, —NHCO. -, -CONH-, or an alkylene-ether group having 1 to 3 carbon atoms, R ⁴ , R ⁵ and R ⁶ each independently represents a phenylene group or a cycloalkylene group, and R ⁷ is a hydrogen atom or carbon number 2 Represents an alkyl group of ˜24 or a fluorine-containing alkyl group, a monovalent aromatic ring, a monovalent aliphatic ring, a monovalent heterocycle, or a monovalent macrocyclic substituent composed thereof.

R ³ in the above formula (3) is preferably —O—, —COO—, —CONH—, or an alkylene-ether group having 1 to 3 carbon atoms from the viewpoint of ease of synthesis.

In addition, R ⁴ , R ⁵ and R ⁶ in the formula (3) are l, m, n, R ⁴ and R ⁵ shown in Table 1 below from the viewpoint of easy synthesis and ability to align liquid crystals vertically. And a combination of R ⁶ is preferred.

When at least one of l, m and n is 1, R ⁷ in formula (3) is preferably a hydrogen atom, an alkyl group having 2 to 14 carbon atoms or a fluorine-containing alkyl group, more preferably A hydrogen atom, an alkyl group having 2 to 12 carbon atoms, or a fluorine-containing alkyl group. When l, m and n are all 0, R ⁷ is preferably an alkyl group having 12 to 22 carbon atoms or a fluorine-containing alkyl group, a monovalent aromatic ring, a monovalent aliphatic ring, a monovalent Heterocycles and monovalent macrocyclic substituents composed of these are preferred, and alkyl groups having 12 to 20 carbon atoms or fluorine-containing alkyl groups are more preferred.

The ability of a polymer having side chains for vertically aligning liquid crystals to align liquid crystals vertically varies depending on the structure of the side chains for vertically aligning liquid crystals, but in general, the side chains for vertically aligning liquid crystals. When the amount of cis is increased, that is, when the content of diamine having a side chain that vertically aligns the liquid crystal contained in the diamine component is increased, the ability to align the liquid crystal vertically increases, and decreases when the content decreases. Moreover, when it has a cyclic structure, compared with what does not have a cyclic structure, there exists a tendency for the capability to orientate a liquid crystal vertically.

(In Formula (4) and Formula (5), A ₁₀ represents —COO—, —OCO—, —CONH—, —NHCO—, —CH ₂ —, —O—, —CO—, or —NH—. , A ₁₁ represents a single bond or a phenylene group, and a represents —R ³ — (R ⁴ ) ₁ — (R ⁵ ) _m — (R ⁶ ) _n —R ⁷ (R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , l, m, and n are the same as defined in the above formula (3), and a ′ is a divalent structure in which one element such as hydrogen is removed from the same structure as a. Represents a group of

(In the formula (6), A ₁₄ is an alkyl group having 3 to 20 carbon atoms which may be substituted with a fluorine atom, and A ₁₅ is a 1,4-cyclohexylene group, or 1,4- A phenylene group, A ₁₆ is an oxygen atom or —COO— * (where a bond marked with “*” is bonded to A ₁₅ ), and A ₁₇ is an oxygen atom or —COO — * ( However, bond marked with "*" is _(CH 2) binds to _{a 2.)} is. in addition, _{a 1} is 0 or 1, _{a 2} is an integer of 2 ~ 10, _{a 3} is 0 or 1)

The bonding position of the two amino groups (—NH ₂ ) in the formula (3) is not limited. Specifically, with respect to the side chain (—R ³ — (R ⁴ ) ₁ — (R ⁵ ) _m — (R ⁶ ) _n —R ⁷ ), 2, 3 positions on the benzene ring, 2, 4 Position, 2, 5 position, 2, 6 position, 3, 4 position, 3, 5 position. Among these, from the viewpoint of reactivity when synthesizing a polyamic acid, positions 2, 4, 2, 5, or 3, 5 are preferable. Considering the ease in synthesizing the diamine, the positions 2, 4 or 3, 5 are more preferable.

Specific examples of the structure of the formula (3) include diamines represented by the following formulas [A-1] to [A-24], but are not limited thereto.

(In the formulas [A-1] to [A-5], A ₁ is an alkyl group having 2 to 24 carbon atoms or a fluorine-containing alkyl group.)

(In Formula [A-6] and Formula [A-7], A ₂ represents —O—, —OCH ₂ —, —CH ₂ O—, —COOCH ₂ —, or —CH ₂ OCO—, and ₃ is an alkyl group having 1 to 22 carbon atoms, an alkoxy group, a fluorine-containing alkyl group or a fluorine-containing alkoxy group.

(In the formulas [A-8] to [A-10], A ₄ represents —COO—, —OCO—, —CONH—, —NHCO—, —COOCH ₂ —, —CH ₂ OCO—, —CH ₂ O—, —OCH ₂ —, or —CH ₂ —, and A ₅ represents an alkyl group having 1 to 22 carbon atoms, an alkoxy group, a fluorine-containing alkyl group, or a fluorine-containing alkoxy group.

(In Formula [A-11] and Formula [A-12], A ₆ represents —COO—, —OCO—, —CONH—, —NHCO—, —COOCH ₂ —, —CH ₂ OCO—, —CH ₂ O—, —OCH ₂ —, —CH ₂ —, —O—, or —NH—, and A ₇ represents fluorine group, cyano group, trifluoromethane group, nitro group, azo group, formyl group, acetyl group, acetoxy Group or hydroxyl group.)

(In Formula [A-13] and Formula [A-14], A ₈ is an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomerism of 1,4-cyclohexylene is a trans isomer. .)

(In the formulas [A-15] and [A-16], A ₉ is an alkyl group having 3 to 12 carbon atoms, and the cis-trans isomerism of 1,4-cyclohexylene is a trans isomer. .)

Specific examples of the diamine represented by the formula (4) include diamines represented by the following formulas [A-25] to [A-30], but are not limited thereto.

(In the formulas [A-25] to [A-30], A ₁₂ represents —COO—, —OCO—, —CONH—, —NHCO—, —CH ₂ —, —O—, —CO—, or —NH—, and A ₁₃ represents an alkyl group having 1 to 22 carbon atoms or a fluorine-containing alkyl group.

Specific examples of the diamine represented by the formula (5) include diamines represented by the following formulas [A-31] to [A-32], but are not limited thereto.

Among these, [A-1], [A-2], [A-3], [A-4], [A-5], [A-5], [A-5], [A-5], [A-5], [A-5], [A-5], [A-5], [A-5], [A-5] The diamines of A-25], [A-26], [A-27], [A-28], [A-29], and [A-30] are preferred.

Such a diamine having a side chain for vertically aligning the liquid crystal or a diamine that develops a high pretilt angle in the liquid crystal is preferably used in an amount of 0 to 50 mol% of the diamine component used for the synthesis of the polyamic acid. Preferably, it is 10 to 40 mol% of the diamine component.

Examples of the diamine having a photoreactive group include a diamine having a photoreactive group such as a vinyl group, an acrylic group, a methacryl group, an allyl group, a styryl group, a cinnamoyl group, a chalconeyl group, a coumarin group, and a maleimide group as a side chain. Although the diamine represented by following General formula (7) can be mentioned, it is not limited to this.

(In the formula (7), R ⁸ is a single bond or —CH ₂ —, —O—, —COO—, —OCO—, —NHCO—, —CONH—, —NH—, —CH ₂ O—, — Represents any one of N (CH ₃ ) —, —CON (CH ₃ ) —, —N (CH ₃ ) CO—, and R ⁹ represents a single bond, or an unsubstituted or substituted carbon atom. Represents an alkylene group of 1 to 20, wherein —CH ₂ — in the alkylene group may be optionally replaced with —CF ₂ — or —CH═CH—, and any of the following groups is not adjacent to each other: And may be replaced by these groups: —O—, —COO—, —OCO—, —NHCO—, —CONH—, —NH—, a divalent carbocycle, and a divalent heterocycle. ¹⁰ vinyl group, an acryl group, a methacryl group, an allyl group, a styryl group, N _(CH 2 CHCH ₂₎ represents a _2, or represented by the following formula structure.)

R ⁸ in the above formula (7) can be formed by a usual organic synthetic method, but from the viewpoint of ease of synthesis, —CH ₂ —, —O—, —COO—, —NHCO —, —NH— and —CH ₂ O— are preferred.

Specific examples of the divalent carbocycle or divalent heterocycle carbocycle or heterocycle for replacing any —CH ₂ — in R ⁹ include the following structures, but are not limited thereto. Is not to be done.

R ¹⁰ is preferably a vinyl group, an acrylic group, a methacryl group, an allyl group, a styryl group, —N (CH ₂ CHCH ₂ ) ₂ or a structure represented by the following formula from the viewpoint of photoreactivity.

In addition, —R ⁸ —R ⁹ —R ¹⁰ in the above formula (7) is more preferably the following structure.

The bonding position of the two amino groups (—NH ₂ ) in the formula (7) is not limited. Specifically, with respect to the side chain (-R ⁸ -R ⁹ -R ¹⁰ ), 2, 3 position, 2, 4 position, 2, 5 position, 2, 6 position on the benzene ring, Examples include positions 3, 4 and 3, 5. Among these, from the viewpoint of reactivity when synthesizing a polyamic acid, positions 2, 4, 2, 5, or 3, 5 are preferable. Considering the ease in synthesizing the diamine, the positions 2, 4 or 3, 5 are more preferable.

Specific examples of the diamine having a photoreactive group include, but are not limited to, the following compounds.

(Wherein X is a single bond or a linking group selected from —O—, —COO—, —NHCO—, —NH—, Y is a single bond, or carbon that is unsubstituted or substituted by a fluorine atom. Represents an alkylene group of 1 to 20.)

In addition, the diamine having such a photoreactive group is preferably used in an amount of 0 to 70 mol%, more preferably 0 to 60 mol% of the diamine component used for the synthesis of the polyamic acid.

The diamine may be one type or two or more types depending on characteristics such as liquid crystal orientation when used as a liquid crystal alignment film, pretilt angle, voltage holding characteristics, stored charge, and response speed of liquid crystal when used as a liquid crystal display element. It can also be used by mixing.

The polymerization reaction between the diamine component and the tetracarboxylic dianhydride component is usually performed in an organic solvent. The organic solvent used in that case is not particularly limited as long as the generated polyamic acid is soluble. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, γ-butyrolactone, isopropyl alcohol. , Methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, Ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene Glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, di Propylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl -3-Methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane, n-pentane, n -Octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, 3-methoxypropion Acid methyl, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-metho Shipuropion propyl, 3-methoxy propionic acid butyl, and the like diglyme or 4-hydroxy-4-methyl-2-pentanone. These may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the above solvent as long as the produced polyamic acid does not precipitate. Moreover, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the produced polyamic acid, it is preferable to use a dehydrated and dried organic solvent.

When the diamine component and the tetracarboxylic dianhydride component are reacted in an organic solvent, the solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride component is used as it is or in an organic solvent. A method of adding by dispersing or dissolving in a solvent, a method of adding a diamine component to a solution in which a tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent, and a tetracarboxylic dianhydride component and a diamine component. And the like, and any of these methods may be used. In addition, when reacting using a plurality of diamine components or tetracarboxylic dianhydride components, they may be reacted in a premixed state, individually or sequentially, and further reacted individually. Low molecular weight substances may be mixed and reacted. In this case, the polymerization temperature can be selected from -20 ° C to 150 ° C, but is preferably in the range of -5 ° C to 100 ° C. In addition, the reaction can be carried out at any concentration, but if the concentration is too low, it will be difficult to obtain a high molecular weight polyamic acid (and polyimide), and if the concentration is too high, the viscosity of the reaction solution will become too high and uniform. Stirring becomes difficult. Therefore, the total concentration of the diamine component and the tetracarboxylic dianhydride component is preferably 1 to 50% by mass, more preferably 5 to 30% by mass in the reaction solution. The initial stage of the reaction is carried out at a high concentration, and then an organic solvent can be added.

In the polymerization reaction of the polyamic acid, the ratio of the total number of moles of the diamine component to the total number of moles of the tetracarboxylic dianhydride component is preferably 0.8 to 1.2. Similar to a normal polycondensation reaction, the molecular weight of the polyamic acid produced increases as the molar ratio approaches 1.0.

The polyamic acid polymerized in this way is, for example, a polymer having a repeating unit represented by the following formula [a].

(In the formula [a], R ₁₁ is a tetravalent organic group derived from a tetracarboxylic dianhydride component such as tetracarboxylic dianhydride represented by the above formula (1) as a raw material, and R ₁₂ is a divalent organic group derived from the diamine component H ₂ N—R ₁₂ —NH ₂ as a raw material, and j represents a positive integer.)

In the above formula [a], each of R ₁₁ and R ₁₂ may be one type and a polymer having the same repeating unit, or R ₁₁ and R ₁₂ may be a plurality of types and a polymer having a repeating unit having a different structure. But you can.

Then, polyimide is obtained by dehydrating and ring-closing such polyamic acid.

Examples of the method for imidizing the polyamic acid include thermal imidization in which the polyamic acid solution is heated as it is, or catalytic imidization in which a catalyst is added to the polyamic acid solution.

The temperature at which the polyamic acid is thermally imidized in the solution is 100 ° C. to 400 ° C., preferably 120 ° C. to 250 ° C., and it is preferable to carry out while removing water generated by the imidation reaction from the outside of the system.

The catalytic imidation of polyamic acid can be carried out by adding a basic catalyst and an acid anhydride to a polyamic acid solution and stirring at -20 to 250 ° C., preferably 0 to 180 ° C. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times of the amic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol of the amido acid group. Is double. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferable because it has a basicity appropriate for advancing the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated. The imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

When recovering the produced polymer (polyimide or polyamic acid) from the reaction solution of the polymer (polyimide or polyamic acid), the reaction solution may be poured into a solvent and precipitated. Examples of the solvent used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer that has been introduced into the solvent and precipitated can be recovered by filtration, and then dried at normal temperature or under reduced pressure at room temperature or by heating. In addition, when the polymer collected by precipitation is redissolved in an organic solvent and reprecipitation and collection is repeated 2 to 10 times, impurities in the polymer can be reduced. Examples of the solvent at this time include alcohols, ketones, and hydrocarbons, and it is preferable to use three or more kinds of solvents selected from these because purification efficiency is further increased.

The dehydration cyclization rate (imidation rate) of the amic acid group of the polyimide contained in the liquid crystal aligning agent of the present invention does not necessarily need to be 100%, and is arbitrarily selected in the range of 0% to 100% depending on the application and purpose. However, 50% to 90% is preferable, and 70% to 86% is more preferable.

The molecular weight of the polyamic acid or polyimide is determined by the GPC (Gel Permeation Chromatography) method in consideration of the strength of the resulting polymer film (liquid crystal alignment film), the workability when forming the polymer film, and the uniformity of the polymer film. The weight average molecular weight measured in (1) is preferably 5,000 to 1,000,000, and more preferably 10,000 to 150,000.

<Solvent>
The solvent contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as it can dissolve the above polyimide and polyamic acid. N, N-dimethylformamide, N, N-dimethylacetamide N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinylpyrrolidone, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme and 4-hydroxy-4 And organic solvents such as methyl-2-pentanone. These may be used alone or in combination.

The solvent in the liquid crystal aligning agent of the present invention preferably has a solvent content of 70 to 99% by mass from the viewpoint of forming a uniform polymer film by coating. This content can be appropriately changed depending on the film thickness of the target liquid crystal alignment film.

<Other components of liquid crystal aligning agent>
In the liquid crystal aligning agent of the present invention, a polymer component is obtained by imidizing a polyamic acid obtained by polymerizing a tetracarboxylic dianhydride represented by the above formula (1) and a diamine component, and the polyamic acid. The polyamic acid obtained by polymerizing the tetracarboxylic dianhydride represented by the above formula (1) and a diamine component may be used. Other polymers may be mixed with at least one polymer selected from polyimides obtained by imidizing polyamic acid. In that case, at least 1 type selected from the polyamic acid obtained by carrying out the polymerization reaction of the tetracarboxylic dianhydride represented by the said Formula (1), and a diamine component, and the polyimide obtained by imidating this polyamic acid. The content of the other polymer other than the total amount of the polymer is 0.5 to 15% by mass, preferably 1.0 to 10% by mass. Other polymers include polyamic acid obtained from a tetracarboxylic dianhydride component and a diamine component that do not contain the tetracarboxylic dianhydride represented by the above formula (1), and polyimide. . Furthermore, polymers other than polyamic acid and polyimide, specifically, polyamic acid ester, acrylic polymer, methacrylic polymer, polystyrene or polyamide are also included.

As long as the liquid crystal aligning agent of the present invention does not impair the effects of the present invention, an organic solvent (also called a poor solvent) that improves the uniformity and surface smoothness of the polymer film when the liquid crystal aligning agent is applied, or A compound may be contained. Furthermore, you may contain the compound etc. which improve the adhesiveness of a liquid crystal aligning film and a board | substrate.

Specific examples of poor solvents that improve film thickness uniformity and surface smoothness include isopropyl alcohol, methoxymethylpentanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol Thor, ethyl carbitol acetate, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl Ether, diethylene glycol, diethylene glycol monoa Tate, Diethylene glycol dimethyl ether, Dipropylene glycol monoacetate monomethyl ether, Dipropylene glycol monomethyl ether, Dipropylene glycol monoethyl ether, Dipropylene glycol monoacetate monoethyl ether, Dipropylene glycol monopropyl ether, Dipropylene glycol monoacetate monopropyl ether , 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexane Xene, propyl ether, dihexyl ether, n- Xanthone, n-pentane, n-octane, diethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, 3-methoxypropionic acid Methyl, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, 1-methoxy-2-propanol 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2 Acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester or Examples thereof include organic solvents having a low surface tension such as isoamyl lactate.

These poor solvents may be used alone or in combination. When the above poor solvent is used, it is preferably 5 to 80% by mass, more preferably 20 to 60% by mass, based on the total organic solvent contained in the liquid crystal aligning agent.

Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. More specifically, for example, F-top EF301, EF303, EF352 (manufactured by Tochem Products), MegaFuck F171, F173, R-30 (manufactured by Dainippon Ink), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard Examples include AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass). The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. .

Examples of the compound for improving the adhesion between the liquid crystal alignment film and the substrate include a functional silane-containing compound and an epoxy group-containing compound. For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltriethoxysilane, Aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3- Ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N- Limethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxy Silane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, ethylene glycol diglycidyl Ether, polyethylene grease Diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2- Dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N ′,-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane or N, N, N ′, N ′,-tetraglycidyl-4,4′-diaminodiphenylmethane.

When using a compound to be adhered to these substrates, the amount is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. Part. If the amount is less than 0.1 part by mass, the effect of improving the adhesion cannot be expected, and if it exceeds 30 parts by mass, the orientation of the liquid crystal may deteriorate.

In the liquid crystal aligning agent of the present invention, in addition to the above poor solvent and compound, as long as the effects of the present invention are not impaired, the purpose is to change the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film. A dielectric or conductive material may be added.

<Liquid crystal alignment film and liquid crystal display element>
The liquid crystal aligning agent of this invention can be used as a liquid crystal aligning film by apply | coating and baking on a board | substrate and performing alignment processing by a rubbing process, light irradiation, etc. In the case of vertical alignment, etc., it can be used as a liquid crystal alignment film without alignment treatment. The substrate used at this time is not particularly limited as long as it is a highly transparent substrate. In addition to a glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can also be used. From the viewpoint of simplifying the process, it is preferable to use a substrate on which an ITO (Indium Tin Oxide) electrode for driving a liquid crystal is formed. In the reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used if only one substrate is used, and a material that reflects light such as aluminum can be used as an electrode in this case.

The method for applying the liquid crystal aligning agent is not particularly limited, but industrially, a method performed by screen printing, offset printing, flexographic printing, an inkjet method, or the like is common. Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, and a spray method, and these may be used depending on the purpose. Since the liquid crystal aligning agent of the present invention suppresses whitening / aggregation, for example, a liquid crystal aligning film excellent in uniformity and transparency can be produced even if the standing time after application to a substrate or the like is increased. Can do.

The drying step after applying the liquid crystal aligning agent on the substrate is not necessarily required, but if the time from application to baking is not constant for each substrate, or if baking is not performed immediately after application, the drying step Is preferably included. The drying is not particularly limited as long as the solvent is removed to such an extent that the shape of the coating film is not deformed by transporting the substrate or the like. For example, a method of drying on a hot plate at a temperature of 40 ° C. to 150 ° C., preferably 60 ° C. to 100 ° C., for 0.5 to 30 minutes, preferably 1 to 5 minutes can be mentioned.

A liquid crystal alignment film (polymer film) can be obtained by baking a coating film formed by applying a liquid crystal aligning agent by the above method. In this case, the firing temperature can be any temperature of 100 ° C. to 350 ° C., preferably 140 ° C. to 300 ° C., more preferably 150 ° C. to 230 ° C., and still more preferably 160 ° C. to 220 ° C. It is. Firing can be performed at an arbitrary time of 5 minutes to 240 minutes. The time is preferably 10 to 90 minutes, more preferably 20 to 80 minutes. For the heating, a generally known method, for example, a hot plate, a thermal circulation oven or an IR (infrared) oven, a belt furnace, or the like can be used. If the thickness of the liquid crystal alignment film after baking is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered. Is 10 to 100 nm. When the liquid crystal is horizontally aligned or tilted, the fired liquid crystal alignment film is treated by rubbing or irradiation with polarized ultraviolet rays. Thus, even when the treatment is performed by irradiation with polarized ultraviolet rays, the liquid crystal alignment film using the liquid crystal aligning agent of the present invention is excellent in UV resistance. Suppressed and has good electrical properties.

The liquid crystal display element of the present invention is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal aligning agent of the present invention by the method described above, and then producing a liquid crystal cell by a known method. For example, the two substrates disposed so as to face each other, the liquid crystal layer provided between the substrates, and the liquid crystal aligning agent of the present invention provided between the substrate and the liquid crystal layer. A liquid crystal display device comprising a liquid crystal cell having a liquid crystal alignment film. As such a liquid crystal display device of the present invention, a twisted nematic (TN) method, a vertical alignment (VA) method, a horizontal alignment (IPS) method, an OCB alignment (OCB: There are various types such as Optically (Compensated Bend).

As a method of manufacturing a liquid crystal cell, prepare a pair of substrates on which the above-mentioned liquid crystal alignment film is formed, spray spacers on the liquid crystal alignment film of one substrate, and make the liquid crystal alignment film surface inside, Examples include a method in which one substrate is bonded and liquid crystal is injected under reduced pressure, or a method in which liquid crystal is dropped on the liquid crystal alignment film surface on which spacers are dispersed and then the substrate is bonded and sealed.

Also, among liquid crystal display elements of a type in which liquid crystal molecules aligned perpendicular to the substrate are responded by an electric field (vertical alignment type), a PSA (Polymer Stained Alignment) in which a photopolymerizable compound is added to the liquid crystal composition in advance. ) Type liquid crystal display and SC-PVA type liquid crystal display to be added to a liquid crystal alignment film (liquid crystal alignment agent), liquid crystal is injected between the pair of substrates on which the liquid crystal alignment film is formed. After sealing, the polymerizable compound may be polymerized by irradiating ultraviolet rays while applying a voltage to the liquid crystal alignment film and the liquid crystal. Even when ultraviolet rays are irradiated in this way, since the liquid crystal alignment film using the liquid crystal aligning agent of the present invention is excellent in UV resistance, deterioration of electrical characteristics such as voltage holding ratio due to ultraviolet irradiation is suppressed, Has good electrical properties.

Examples of the liquid crystal include a positive liquid crystal having a positive dielectric anisotropy and a negative liquid crystal having a negative dielectric anisotropy. Specifically, for example, MLC-2003, MLC-6608, MLC-6609 manufactured by Merck & Co., Inc. Etc. can be used.

As described above, since the liquid crystal display element produced using the liquid crystal aligning agent of the present invention has a liquid crystal alignment film excellent in ultraviolet resistance, the liquid crystal display element used in an environment exposed to ultraviolet rays. Even when used as a liquid crystal alignment film, the deterioration of electrical characteristics such as voltage holding ratio is suppressed, the electrical characteristics are excellent, and the reliability is excellent.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not construed as being limited to these. Abbreviations used in Examples and Comparative Examples are as follows.

<Tetracarboxylic dianhydride>
PPHT: N, N′-bis (1,2-cyclohexanedicarboxylic anhydride-4-yl) carbonyl-1,4-phenylenediamine represented by the following formula PSHT: N, N′-bis ( 1,2-cyclohexanedicarboxylic anhydride-4-yl) carbonyl-3,3′-diaminodiphenylsulfone CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride TDA: 3,4-dicarboxy- 1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride

<Diamine>
BAPU: 1,3-bis (4-aminophenethyl) urea DDM: 4,4′-diaminodiphenylmethane DADA: N, N-diallyl-2,4-diaminoaniline APC16: 1,3-diamino-4-hexadecyl Oxybenzene APC18: 1,3-diamino-4-octadecyloxybenzene p-PDA: p-phenylenediamine

<Organic solvent>
NMP: N-methyl-2-pyrrolidone BCS: 2-butoxyethanol

The measurement method performed in this example will be described below.
<Measurement of molecular weight>
The molecular weights of polyamic acid and polyimide were determined by measuring the polyamic acid and polyimide with a GPC (room temperature gel permeation chromatography) apparatus, and calculating the number average molecular weight and weight average molecular weight as polyethylene glycol and polyethylene oxide equivalent values.
GPC device: manufactured by Shodex (GPC-101)
Column: manufactured by Shodex (series of KD803 and KD805)
Column temperature: 50 ° C
Eluent: N, N-dimethylformamide (as additive, lithium bromide-hydrate (LiBr · H ₂ O) 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) 30 mmol / L , Tetrahydrofuran (THF) at 10 ml / L)
Flow rate: 1.0 ml / min Standard sample for preparation of calibration curve: TSK standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, 30000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weight: about 12000, 4000, 1000) manufactured by Polymer Laboratory .

<Measurement of imidization ratio>
The imidation ratio of polyimide was measured as follows.
20 mg of polyimide powder was placed in an NMR sample tube, and 0.53 ml of deuterated dimethyl sulfoxide (DMSO-d ₆ , 0.05% TMS (tetramethylsilane) mixture) was added and completely dissolved. This solution was measured for proton NMR at 500 MHz with an NMR measuring instrument (JNM-ECA500) manufactured by JEOL Datum. The imidation rate is determined based on protons derived from structures that do not change before and after imidation as reference protons, and the peak integrated value of these protons and proton peaks derived from NH groups of amic acid appearing in the vicinity of 9.5 ppm to 10.0 ppm. It calculated | required by following Formula using the integrated value.
Imidization rate (%) = (1−α · x / y) × 100
In the above formula, x is the proton peak integrated value derived from the NH group of the amic acid, y is the peak integrated value of the reference proton, and α is one NH group proton of the amic acid in the case of polyamic acid (imidation rate is 0%). The number ratio of the reference protons.

(Synthesis Example 1)
Using 1.33 g of PPHT as the tetracarboxylic dianhydride component and 0.32 g of p-PDA as the diamine component, the mixture was reacted in 14.93 g of NMP at room temperature for 18 hours to obtain a solid content of polyamic acid (PAA-1). A solution with a concentration of 10 wt% was obtained.

(Synthesis Examples 2 to 10)
A solution of polyamic acids (PAA-2 to PAA-10) of Synthesis Examples 2 to 10 was obtained using the same method as in Synthesis Example 1 except that the composition shown in Table 2 was used.

(Synthesis Example 11)
12.15 g of NMP was added to 15.1 g of the polyamic acid (PAA-1) solution obtained in Synthesis Example 1 and diluted to prepare a polyamic acid solution having a solid content concentration of 6 wt%. To this polyamic acid solution, 2.95 g of acetic anhydride and 1.37 g of pyridine were added and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 150 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-1). As a result of measuring the imidation ratio of polyimide (SPI-1), it was 79%.

(Synthesis Examples 12 to 18)
A polyimide (SPI-2 to SPI-8) powder of Synthesis Examples 12 to 18 was obtained in the same manner as in Synthesis Example 11 except that the composition shown in Table 3 was used.

(Example 1)
3.25 g of NMP was added to 3.25 g of the polymer (polyamic acid PAA-1) solution obtained in Synthesis Example 1, and the mixture was stirred at room temperature for 3 hours. The polyamic acid was completely dissolved at the end of stirring. Furthermore, 1.63 g of BCS was added to this solution and stirred at room temperature for 1 hour to obtain a polymer solution (A1) having a solid content concentration of 4.0 wt%. This polymer solution becomes a liquid crystal aligning agent for forming a liquid crystal alignment film as it is.

(Examples 2-7, Comparative Examples 1-2)
The polymer solutions (A2 to A7) of Examples 2 to 7 and the polymer solutions (B1 to B2) of Comparative Examples 1 and 2 were used in the same manner as in Example 1 except that the compositions shown in Table 4 were used. Got.

(Example 8)
NMP7.53g was added to the polymer (polyimide SPI-1) 0.50g obtained in the said synthesis example 11, and it stirred at room temperature for 3 hours. The polyimide was completely dissolved at the end of stirring. Further, 2.01 g of BCS was added to this solution and stirred at room temperature for 1 hour to obtain a polymer solution (A8) having a solid content concentration of 5.0 wt%. This polymer solution becomes a liquid crystal aligning agent for forming a liquid crystal alignment film as it is.

(Examples 9 to 13, Comparative Examples 3 to 4)
A polymer solution of Examples 9 to 13 (A9 to A13) and a polymer solution of Comparative Examples 3 to 4 (B3 to B4) were used in the same manner as in Example 8 except that the compositions shown in Table 5 were used. Got. In any of Examples 9 to 13, as in Example 8, the polyimide was completely dissolved at the end of stirring.

[Production of liquid crystal cell]
The polymer solution (A1) obtained in Example 1, that is, the liquid crystal aligning agent (A1) was filtered through a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, and then heated on an 80 ° C. hot plate for 80 seconds. After drying, baking was performed at 230 ° C. for 10 minutes to obtain a coating film (polyimide film) having a film thickness of 100 nm. This polyimide film is rubbed with a rayon cloth (roll diameter: 120 mm, rotation speed: 1000 rpm, moving speed: 50 mm / sec, pushing amount: 0.3 mm), and then subjected to ultrasonic irradiation for 1 minute in pure water and at 80 ° C. for 10 minutes. It dried and formed the liquid crystal aligning film. Two substrates with such a liquid crystal alignment film are prepared, a spacer of 6 μm is installed on the surface of the liquid crystal alignment film of one substrate, and then combined so that the rubbing directions of the two substrates are orthogonal to each other. The periphery was sealed and the empty cell having a cell gap of 6 μm was produced. Liquid crystal (MLC-2003 (C080), manufactured by Merck Japan Co., Ltd.) was vacuum-injected into this cell at room temperature, and the inlet was sealed to obtain a liquid crystal cell in which the liquid crystal was twisted by 90 degrees.

In addition, the liquid crystal aligning agents (A2 to A13) obtained in Examples 2 to 13 and the liquid crystal aligning agents (B1 to B4) obtained in Comparative Examples 1 to 4 were also used. A liquid crystal cell was produced using the same method as the alignment agent (A1).

[Voltage holding ratio (VHR) evaluation]
The voltage holding ratio was evaluated by applying a voltage of 4 V to the obtained liquid crystal cell at a temperature of 90 ° C. for 60 μs, measuring the voltage after 16.67 ms, The variation from the value was calculated as the voltage holding ratio. The voltage holding ratio was measured using a voltage holding ratio measuring device VHR-1 manufactured by Toyo Technica. The evaluation results (described as “initial” in Table 6) are shown in Table 6.

Next, the liquid crystal cell was irradiated with 1J of 365 nm ultraviolet light, and VHR after the ultraviolet irradiation was similarly evaluated. The evaluation results (described as “UV1J” in Table 6) are shown in Table 6.

[Evaluation of pretilt angle]
About the obtained liquid crystal cell, after heating at 120 degreeC for 1 hour, the pretilt angle was measured. The pretilt angle was measured by “Axo Scan” of AxoMetrix using the Mueller matrix method. The results are shown in Table 6.

[Evaluation of whitening and aggregation characteristics]
About 0.1 ml of each liquid crystal aligning agent (polymer solution) obtained in Examples 1 to 13 and Comparative Examples 1 to 4 was dropped on a Cr substrate and left in an environment at a temperature of 23 ° C. and a humidity of 55%. The vicinity of the end of the droplet was observed with a microscope every 10 minutes. The observation was performed at a magnification of 100 times. The case where the aggregate was generated for 10 minutes or less was evaluated as x, more than 10 minutes for less than 1 hour, Δ for 1 hour or more and less than 3 hours, and ○ for 3 hours or more. The evaluation results are shown in Table 6.

As shown in Table 6, when the liquid crystal aligning agents (polymer solutions) of Examples 1 to 13 containing polyamic acid or polyimide using the tetracarboxylic dianhydride represented by the formula (1) as a raw material were used Compared with Comparative Examples 1 to 4, it was found that the change in the voltage holding ratio before and after the ultraviolet irradiation was small, and the performance deterioration due to the ultraviolet irradiation was remarkably reduced.

In addition, the liquid crystal aligning agents (polymer solutions) of Examples 1 to 13 containing polyamic acid and polyimide made from tetracarboxylic dianhydride represented by the formula (1) are 3 in the evaluation of whitening / aggregation characteristics. It was found that no agglomerates were formed even when allowed to stand for more than a period of time, and excellent whitening / aggregation characteristics were provided. In addition, it was also confirmed that the liquid crystal aligning agents of Examples 1 to 13 achieve good alignment (pretilt angle) of the liquid crystal by the alignment treatment.

Claims

At least one polymer selected from a polyamic acid obtained by polymerizing a tetracarboxylic dianhydride represented by the following formula (1) and a diamine component and a polyimide obtained by imidizing the polyamic acid; And a liquid crystal aligning agent containing a solvent.
The liquid crystal aligning agent according to claim 1, wherein the polymer is polyimide.
A liquid crystal alignment film obtained by using the liquid crystal aligning agent according to claim 1.
A liquid crystal display element comprising the liquid crystal alignment film according to claim 3.